1. Field of the Invention
The invention relates to a charging station for electric-powered vehicles, more particularly to a charging station capable of automatic control of charging current that is supplied to a plurality of loads.
2. Description of the Related Art
The battery of an electric-powered vehicle is generally charged at a charging station that is accessible to the public. While a charging station is capable of charging the batteries of a number of electric-powered vehicles at the same time, the total amount of charging current supplied by the charging station at any time should not exceed a rated value. For example, if a charging station is capable of charging the batteries of four electric-powered vehicles simultaneously, and the initial load current that should be supplied to charge the battery of each of the electric-powered vehicles is 8 amperes, the rated current value for the charging station should be at least 32 amperes to prevent occurrence of an overload. Thus, aside from the need to coordinate with the local electric power company in view of the large current requirement, the power distribution network of the charging station should also be designed to handle such large current flows.
However, it is noted that the charging current requirement of a battery decreases from a maximum value (i.e. the battery is fully discharged) to a minimum value (i.e. the battery is fully charged) as the charging operation progresses. As such, it is very unlikely that the charging station will operate at full load conditions most of the time. The conventional charging station is thus uneconomical since it is designed under full load conditions.